For some of the mixes, red sea coral pro comes to mind, they really oversaturate some of the parameters (e.g., alk) so that people have to dose less maybe? In that case, if there is more alk than can sustainable stay dissolved at whatever conditions they are mixed at (temperature/pH mostly), some of the alk or caco3 or whatever is supersaturated will precipitate out as scale.
If that's what you mean by potency I can see that, but I would be careful basing decisions on things that cant be measured or defined.

Because they are already in relatively stable concentrations in salt. When we dose, the area that is dosed is saturated with more than the water can dissolve normally in a short time. When both get dosed at causes them to more or less combine and form into a solid which cannot dissolve readily.

You can use chlorine test strips every so often to test break through after your carbon filter. They have a recommended total flow range, so just calculate the total flow and start testing when you get to maybe 75% of the flow ? Remember that produced water is only a fraction of the total water that goes through the carbon filter. I think most membranes reject 3:1 for produced water. So for every gallon of produced water, three gallons are rejected. You calculate your total flow through carbon on 4 gallons total flow instead of 1 gallon of produced water. Sent from my iPhone using Tapatalk Pro

Welcome. The # of stages isn't super relevant, but what is important is what you do with those stages. The key piece for CoA water is that we use chloramines. That means that any old carbon block wont do. Once chloramines break through the carbon block, they degrade the RO membrane and quickly deplete your DI resin.
Check this video out for more info:
The minimum I'd recommend you run is prefilter->universal carbon block->RO membrane->DI Resin. So that would be 5 stages *at a minimum*. I run redundant carbon and redundant DI resin (i.e., 2 carbons, 2 DI resins) and then swap in new cartridges in the last position and move the older cartridge up a position. For example I have OldCarbon1, OldCarbon2. Old Carbon2 becomes NewCarbon1 and NewCarbon2 is a totally new carbon block. I do the same with DI resin. Hope this helps.

As the calcium carbonate in the coralline algae is dissolved by the vinegar, it's "acid power" diminishes. How much it diminishes is a function of the strengh of the acid (vinegar is a weak acid) and the solubility of the CaCO3 in the coralline algae. It doesn't take a lot of carbonate to totally deaden the dissolution power.
I'm not a chemist but I did get a graduate degree with chemistry partially in the title.
Strong acids are a different story. I used to clean out groundwater remediation systems with straight up hydrochloric acid (aka muriatic acid for pool work and concrete etching), which was in retrospect pretty dangerous/stupid, and to stabilize the water we were making we would add boxes of baking soda (sodium bicarbonate). It would really only fiz after the first box, which is the production of CO2 from breaking down the NaHCO3 by HCl. However the pH was low until we added many, many boxes.